The pion-condensation threshold in symmetric ($N=Z$) nuclear matter at finite temperatures $0\le k_{B}T\le 100$ MeV is calculated. The influence of thermally excited $\Delta$ isobars—present in the nucleon medium—on the threshold is investigated and found to be moderately repulsive (i.e., raising the threshold density).

NUCLEAR STRUCTURE Pion condensation in nuclear matter, thermal $\Delta$ isobars at finite temperature.

• Received 26 March 1981

DOI:https://doi.org/10.1103/PhysRevC.24.1691